Conformational Heterogeneity and Frustration of the Tumor Suppressor p53 as Tuned by Punctual Mutations

The conformational heterogeneity of the p53 tumor suppressor, the wild-type (p53wt) and mutated forms, was investigated by a computational approach, including the modeling and all atoms of the molecular dynamics (MD) simulations. Four different punctual mutations (p53R175H, p53R248Q, p53R273H, and p53R282W) which are known to affect the DNA binding and belong to the most frequent hot-spot mutations in human cancers, were taken into consideration. The MD trajectories of the wild-type and mutated p53 forms were analyzed by essential dynamics to extract the relevant collective motions and by the frustration method to evaluate the degeneracy of the energy landscape. We found that p53 is characterized by wide collective motions and its energy landscape exhibits a rather high frustration level, especially in the regions involved in the binding to physiological ligands. Punctual mutations give rise to a modulation of both the collective motions and the frustration of p53, with different effects depending on the mutation. The regions of p53wt and of the mutated forms characterized by a high frustration level are also largely involved in the collective motions. Such a correlation is discussed also in connection with the intrinsic disordered character of p53 and with its central functional role.     

微机自控节能技术在乳化液泵站的应用

乳化液泵站微机全自动控制和综合保护装置的最大特点,是根据工作面用液量自动控制乳化液泵开机、停机,能自动执行配液、补液等操作,并配置了吸空、低油位、低油压、过油温四大保护,达到安全运行、节能降耗的目的.文章介绍节能型YKZ-2B乳化液泵站微机全自动控制和综合保护装置原理、工作特点,并论述使用中注意的问题及其节能效果.     

Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics

The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown in a glass capillary in situ and the structures of high- (238–270 K) and low-temperature (100–230 K) phases were studied in detail. In the temperature interval 230–238 K, a phase transition with rather low enthalpy (−1.04(7) kcal/mol) was detected. It was found that phase transition is accompanied by change of conformation of cyclosiloxane moiety from boat-saddle (cradle) to chair. According to PBE0/6-311G(d,p) calculation of isolated D4, such conformation changes are characterized by a low barrier (0.07 kcal/mol). The character of molecular thermal motion and the path of phase transition were established with combination of periodic DFT calculations, including molecular dynamics and metadynamics. The effect of crystal field led to an increase in the calculated phase transition barrier (4.27 kcal/mol from low- to high-temperature phase and 3.20 kcal/mol in opposite direction).     

高效导向筛板的研究与应用

详细介绍了高效导向筛板的结构,指出其在机械结构上有两项改进,即导向孔和鼓泡促进器,这大大提高了塔板的性能。研究了高效导向筛板的加工过程及分离效率,并给出了其在PVC工业中的应用实例。     

异构型无线传感器网络的生命周期

研究了一种异构型无线传感器网络的能量效率问题。该网络是具有不同初始能量的两类传感器节点以不同的数量均匀地分布在监测区域形成的,它基于簇的方式周期性采集数据传输到网关(sink)节点。本文对簇头节点和成员节点的能量消耗进行了数学建模,并且分析了网络的生命周期与检测区域参数之间的关系。通过理论分析和仿真结果得到了最大网络生命周期的最佳分簇数目以及不同层次节点的能量分配比例,并进一步导出了网络生命周期与簇头能量配置的关系。     

煤和瓦斯突出机理的流变假说

基于煤与瓦斯突出能量理论,建立了突出煤体三维结构应力模型,并利用弹塑性力学相关知识和数学求解方法推导了突出煤体的瓦斯弹性势能和瓦斯内能方程,为钻孔造穴诱突技术应用提供理论依据和实现路径。现场试验了钻孔水力造穴诱突、爆破诱突2种诱突技术措施,结果表明,钻孔造穴诱突过程的能量耗散机制符合推导的瓦斯能量方程和结构应力模型。针对试验矿井实际条件,2种诱突技术措施应用时存在一个阈值,当试验矿井煤层瓦斯含量大于9 m³/t时宜采用水力造穴诱突技术,反之宜采用爆破诱突技术。实践表明,2种诱突技术措施均能使试验矿井瓦斯治理效果显著提高。

     

温度对煤吸附瓦斯的动力学特性影响实验研究

为了探究温度对中等程度焦煤中甲烷的吸附解吸特征的影响规律,采用等温吸附实验和甲烷解吸实验分析煤样在不同温度下的变化情况,结合Langmuir模型、等量吸附热、煤表面自由能和解吸量模型对所得实验数据进行分析。结果表明：随着温度的升高,甲烷吸附量及Langmuir吸附常数a、b均呈现下降的趋势;煤的吸附是放热过程,伴随着甲烷吸附量的增大等量吸附热随之增加;温度会导致煤表面自由能改变,温度升高煤表面自由能变化值减小,表现为甲烷吸附量减少;解吸曲线具有明显的Langmuir特征,温度升高会促进甲烷解吸,且最初10 min中的解吸速率增速较快。

     

综掘工作面压风分流控除尘技术研究与应用

为解决快速掘锚工作面的粉尘污染问题,以寸草塔煤矿22120工作面运输巷快速掘锚工作面为研究对象,通过FLUNET软件建立数值模拟模型,研究并优化控风、抽风风量的匹配关系,并结合现场实际应用进行验证,得到合适的掘锚工作面配套方式及最优工艺参数。研究结果表明：将除尘器安设于掘锚机顶部,并采用“附壁风筒+挡尘帘”进行控风除尘的工艺配套方式,掘锚工作面的粉尘质量浓度得到显著降低;当除尘器抽出风量为405 m³/min(即抽压风量比为0.9)时,工作面降尘效果明显,呼吸性粉尘的降尘效率达到95%以上,极大改善了掘锚工作面的作业环境。

     

浅层地热能开发回灌井施工技术研究——以郑州市东、西部新城区为例

地下水回灌是浅层地热能开发利用中不可缺少的环节,回灌井是实施回灌的关键设施,其施工技术是影响回灌效果的重要因素。选取郑州市东部新城区、西部新城区浅层地热能开发的回灌井为研究对象,分析不同区域地质条件的差异,通过回灌井结构分析地下水的回灌机理,论述影响回灌效果的因素。结合试验井施工情况,论述泥浆正循环钻进、泵吸反循环钻进、冲击钻进等不同钻进工艺的适用条件和施工中存在的问题,以及钢筋砼管、钢管和U-PVC管等不同成井管材对回灌效果的影响,探索提高单位回灌量的针对性措施,为今后郑州市及周边地区浅层地热能开发回灌井的施工提供参考。     

浅层地热能地下换热系统适宜性评价与优化设计——以郑州市浅层地热能示范工程为例

地热资源的开发利用对减少CO2排放和抑制全球气候变化能起到积极的作用。目前,国内浅层地热能地下换热主要有地下水换热系统和地埋管换热系统2种方式,其共同优点是能源利用系数高、安全稳定、零污染排放等,但在换热效率、开发利用条件、空间占用等方面各有利弊。本文叙述了浅层地热能地下换热系统适宜性评价指标,结合郑州市浅层地热能示范工程建设项目,分别进行了抽水与回灌试验、岩土热物性参数测试、地层热响应试验等现场试验,对浅层地热能2种换热方式的适宜性进行了分析比较,得出建设区岩土具有较高的导热系数和容积比热容,有利于热量的传导与保持;但区域水位埋深浅,现场试验回灌量仅107.37 m3/d,回灌能力较差。相比之后,优化设计并选择了更适用于建设区浅层地热能开发利用的地下埋管换热系统。